The present invention relates to catheters, and more particularly to inflation control devices for such catheters.
A various assortment of catheters, such as endotracheal tubes and Foley catheters, have been proposed for use on patients. Such catheters are normally constructed with a shaft having a main lumen, an inflatable balloon secured to a distal end of the shaft, and an inflation lumen extending through a side arm of the catheter and along the shaft, with the inflation lumen communicating with the balloon. The catheters are normally provided with a valve on the side arm, which is located outside the patient during use of the catheter, in order to control inflation and deflation of the balloon. Although such catheters are in common use, a persistent problem with catheters has been determining an accurate inflation pressure in the balloon.
In the case of endotracheal tubes, the balloon or cuff if properly inflated seals off the trachea and retains the endotracheal tube in place. If the balloon has been inflated to a pressure less than the necessary amount, then the positive pressures developed by a respirator during use of the endotracheal tube may cause loss of seal by the cuff. On the other hand, if the cuff is overinflated, the contact of the cuff against the trachea frequently results in pressure necrosis of the tracheal mucosa. Thus, it is necessary that the cuff or balloon be inflated to a pressure sufficient to maintain a seal in the trachea, yet sufficiently small to minimize the possibility of necrosis. Of course, the inflated balloon is not directly visible to the physician, but even if visible, it is difficult to determine whether or not the balloon has been inflated to the desired pressure.